To mass produce norimaki (sushi rice, or vinegared rice and ingredients rolled in dry layer), there has been proposed a cooked rice mold apparatus as disclosed in Japanese Patent Application Publication No. 2002-45129, for example. In this cooked rice mold apparatus, cooked rice supplied from a hopper into which sushi rice, or rice seasoned with vinegar is charged is first shaped by a rolling section into the shape of a plate and then spread over dry layer placed on a rolling-up bamboo plate, and the sushi rice, or the rice seasoned with vinegar is rolled in dry layer into the shape of a rod by deforming the rolling-up bamboo plate in cylindrical form.
With this apparatus, everyone can easily make norimaki (vinegared rice and ingredients rolled in dry layer) without the need of skills of sushi chefs, simply by placing layer on the rolling-up bamboo plate, putting ingredients on the sushi rice or the rice seasoned with vinegar that is automatically supplied, and operating buttons.
In Japanese Patent Application Publication No. 2002-45129 above, the rolling-up bamboo plate is composed by rotatably connecting four plate members, and these plate members are connected by use of a link arm so that plate-like pieces on both sides are folded up so as to be opposed to each other, whereby a cylindrical space for rolling up the sushi rice, or the rice seasoned with vinegar is formed inside.
In this type of a cooked rice mold apparatus, it is necessary to change the supply amount of sushi rice according to the thickness of rolled sushi. In the above-described conventional apparatus, which has a first rolling roller pair and a bottom rolling roller pair arranged at two levels of a rolling section, the supply amount has been adjusted by adjusting the roller spacing of the bottom rolling roller pair on the downstream side, with the roller spacing of the top rolling roller pair on the upstream side kept constant.
In the conventional cooked rice mold apparatus, however, because the roller spacing of the top rolling roller pair on the upstream side is constant, the supply amount of sushi rice retained in the rolling section is constant. Therefore, even when the roller spacing in the bottom rolling roller pair is made wide, it has been difficult to adjust the supply amount because of low density of sushi rice, although the sushi rice becomes seemingly thick.
In order to increase the density of sushi rice, more sushi rice is supplied to the bottom rolling roller pair on the downstream side by either increasing the rotation speed of the top rolling roller pair on the upstream side or reducing the rotation speed of the bottom rolling roller pair. However, when the rotation speed of the top rolling roller pair on the upstream side is increased, fine thickness control is difficult because the flow velocity varies according to the condition of sushi rice (viscosity, moisture and temperature). Furthermore, when the rotation speed of the bottom rolling roller pair is reduced, the molding time becomes long, resulting in a decrease in production.
To solve the above-described problems, therefore, the object of the present invention is to provide a cooked rice mold apparatus that can easily adjust the supply amount of sushi rice.